Joe DiMaggio Jr., the only son of the legendary Yankee Clipper, has died at age 57 – just five months after he was a pallbearer at the funeral of his estranged 84-year-old father.

DiMaggio Jr. died late Friday night in an Antioch, Calif., hospital, apparently of natural causes.

He was not breathing and had no heartbeat when he arrived by ambulance at Sutter Delta Medical Center – and he was pronounced dead at 11:25 p.m. California time, spokeswoman Nancy Monfort said.

DiMaggio Jr. – who had not spoken to his dad in the two years before the slugger’s March death – struggled most of his life under the weight of his famous father’s name.

He had a history of drug and alcohol abuse, got into scrapes with the law and was often homeless.

“He lived in the shadow of his father and could not rise above that,” cousin Marie Amato Goodman said.

“He really was not a bad boy. He was confused about a lot of issues in his life,” Goodman said.

DiMaggio Jr. was the only child of the baseball great and his first wife, actress Dorothy Arnold, who wed in 1939.

The couple divorced after three years and shared custody, but the arrangement was strained when DiMaggio married Marilyn Monroe in 1954. The younger DiMaggio grew close to the blond icon and was one of the last people to speak to her before her death of a drug overdose in 1962.

Described as “brilliant,” DiMaggio Jr. entered Yale in 1960 – but quit to do a stint in the Marines.

He disappeared into a quiet life in the West, marrying an older woman and adopting her two daughters, Kathie and Paula.

The marriage ended in divorce – leaving the younger DiMaggio a lonely recluse who lived in a squalid trailer.

Earlier this year, he told “Inside Edition” in a rare interview that he loved his father and enjoyed being a “free spirit.”

But ex-wife Sue Adams told Esquire magazine DiMaggio Jr. was still bitter from a lonely childhood spent in camps and boarding schools.

Despite the split, DiMaggio Jr. helped carry his father’s casket and received a $20,000-a-year trust fund in his father’s will.